01 - Combine flour, sugar, salt, and yeast in a large bowl, keeping yeast separate from salt. Pour in lukewarm milk, melted butter, and cracked egg. Mix thoroughly until a sticky, shaggy dough forms.
02 - Knead the dough on a lightly floured surface for 7 to 10 minutes until smooth and elastic. Transfer to a greased bowl, cover, and let rise in a warm place for 1 hour until doubled in volume.
03 - Punch down the risen dough to release air. Shape into a rectangle, wrap tightly, and refrigerate for 30 minutes to firm the gluten structure.
04 - On a lightly floured surface, roll the chilled dough into a 12 x 16-inch rectangle. Arrange cold butter slices over two-thirds of the dough surface, leaving a 1-inch border.
05 - Fold the unbuttered third of dough over the center buttered section, then fold the remaining third over the top to create a neat rectangle. Rotate the dough 90 degrees so the open edges face you.
06 - Roll the dough again to a 12 x 16-inch rectangle. Perform a letter fold by folding into thirds. Wrap and refrigerate for 30 minutes.
07 - Repeat the rolling, folding, and chilling process two more times for a total of three laminating turns. After the final fold, refrigerate for 30 minutes.
08 - Roll the laminated dough to approximately 8 x 16 inches. Starting from a short edge, roll tightly into a cylinder shape, pressing gently to seal.
09 - Place the loaf seam-side down in a greased 9 x 5-inch loaf pan. Cover loosely and let rise in a warm place until doubled, about 1 hour.
10 - Preheat oven to 375°F. Whisk together egg and milk for the egg wash. Brush the entire surface of the risen loaf evenly with the mixture.
11 - Bake for 35 to 40 minutes until deeply golden brown and the loaf sounds hollow when tapped on the bottom. Tent with aluminum foil if the top browns too quickly.
12 - Let the bread cool in the pan for 10 minutes, then transfer to a wire rack. Cool completely before slicing for clean, neat cuts.